1. Field of the Invention
The present invention relates to a combustion chamber for ignition of a fuel with a temperature graduation flow. It also relates to a method of operating such a combustion chamber.
2. Discussion of Background
In the case of combustion chambers, in particular annular combustion chambers having a wide load range, the problem of how the service life of the blades of the turbine arranged directly downstream of the annular combustion chamber can be maximized at high temperatures of the hot gases and while maintaining low pollutant emissions repeatedly occurs. In general it can be said that the blades of the turbine are acted upon integrally with uniformly hot gases. In addition it may be noted that the blades of the turbine are subjected to even greater thermal loading in the case of an annular combustion chamber operated according to a self-ignition method. To ensure that self-ignition takes place upstream of the turbine, temperatures are aimed at which have a certain safety margin against extinction of the flame, as a result of which the blades are actually acted upon at a higher temperature than is the case in conventional combustion chambers. Here, allowance must be made for the fact that the blades have no uniform strength resistance over their radial extent, for which reason conventional blade cooling comes up against limiting factors, for certain parts of the blades ought to be cooled to a greater extent and others to a lesser extent, but up to now it has not been possible to solve this problem satisfactorily. The thermally highly loaded blade bases especially do not contribute directly to the efficiency of the fluid-flow machine, so that a lower temperature could actually prevail there without having to fear efficiency losses because of that, in which case it is assumed to be known that the average temperature of the hot gases is responsible for the resulting gain in thermal efficiency. As far as is known, no feasible solution has been disclosed up to now which is able to act upon specific parts of the blades at different temperatures without losses of efficiency and at lower pollutant emissions, in particular as far as the NOx is concerned.